It is well known that film-type cooling tower fill packs are stronger and easier to install when the sheets are bonded together well. Some fill sheet bonding techniques include chemical welding, snap buttons, rods, screws, nails, and thermal bonding. Chemical welding is the most common and is also usually the strongest, but requires the use of solvents and a flash time for the bond to set. Chemical welding is usually performed at a different location from the installation due to restrictions on solvents and the extreme amount of time necessary to allow the pack to cure. Snap buttons can be used at the installation site, but the joints are easily detached. Rods, screws, and nails require additional parts to be added to the pack, which increases cost. These joints are also not as substantial as chemical welding. Thermal bonding has, until this invention, been difficult to achieve a satisfactory bond. Existing methods also have difficulty reaching the interior bond sites in the pack, leading to a weak pack. This invention overcomes the current limitations for on-site bonding as well as producing a factory bond that eliminates the need for solvents.